Well, there is a difference between putting yourself in another perspective mentally, and putting yourself there emotionally. Even a sophisticated computer could reason the world from the perspective of other being, but to connect with the experience of the other, you need to be there empathically. That is how the seeming paradox gets obliterated: although psychopaths can understand what the other person thinks and predict their feelings, they themselves cannot emotionally get in their shoes, and thus, internally, don´t give a shit about the other´s well being(unless it suits them to achieve something). I´m not a researcher, but knew some psychopaths in real life and thus, I can tell you this is objectively true.